From: Frederic Lecaille <flecaille@haproxy.com>
Date: Fri, 24 Jul 2026 10:06:23 +0000 (+0200)
Subject: BUG/MINOR: haload: fix CPU topology detection by omitting forced "nbthread"
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=be66535ab904ed76d8c8165249ab0db5a570e359;p=thirdparty%2Fhaproxy.git

BUG/MINOR: haload: fix CPU topology detection by omitting forced "nbthread"

Always writing "nbthread" in the generated global configuration forced a
static thread count, preventing HAProxy from using its automatic CPU
topology detection and correct core binding. This caused severe performance
degradation on large multi-core machines. Fix this by omitting the "nbthread"
directive when -t is not explicitly specified, while ensuring <arg_thrd>
is properly initialized to global.nbthread for internal calculations such as
connection and request rates.

Also ensure <arg_thrd> <= <arg_usr> when -R is specified for internal
calculations.
---

diff --git a/src/haload.c b/src/haload.c
index e13e3cf77..91b036ca1 100644
--- a/src/haload.c
+++ b/src/haload.c
@@ -100,7 +100,7 @@ int arg_rcon = -1;     // max requests per conn
 int arg_reqs = -1;     // max total requests
 int arg_serr;          // stop on first error
 int arg_slow;          // slow start: delay in milliseconds
-int arg_thrd = 1;      // number of threads
+int arg_thrd;          // number of threads
 int arg_usr = 1;       // number of users
 int arg_wait = 10000;  // I/O time out (ms)
 
@@ -1916,6 +1916,20 @@ static int hld_init(void)
 	if (!hld_cfg_finalize())
 		goto err;
 
+	/* This is the location to initialize the default value for <arg_thrd>.
+	 * Indeed, global.nthread is initialized late(after the parsing step).
+	 */
+	if (arg_thrd == 0)
+		arg_thrd = global.nbthread;
+
+	if (arg_rate && arg_thrd > arg_usr) {
+		ha_alert("Thread count (%d) must not exceed connection count (%d)\n",
+		         arg_thrd, arg_usr);
+		goto err;
+	}
+
+	BUG_ON(arg_thrd != global.nbthread);
+
 	/* Consider the case where <arg_reqs> < <arg_usr> */
 	if (arg_reqs != -1 && arg_reqs < arg_usr)
 		arg_usr = arg_reqs;
diff --git a/src/haload_init.c b/src/haload_init.c
index 8da0b8f95..82770eae6 100644
--- a/src/haload_init.c
+++ b/src/haload_init.c
@@ -28,7 +28,7 @@ static void  hld_usage(char *name, int argc)
 		"        -n <reqs>        maximum total requests (-1)\n"
 		"        -r <reqs>        number of requests per connection (-1)\n"
 		"        -s <time>        soft start: time in sec to reach 100%% load\n"
-		"        -t <threads>     number of threads (1)\n"
+		"        -t <threads>     force number of threads (nbthread)\n"
 		"        -u <users>       number of users (1)\n"
 		"        -w <time>        I/O timeout in milliseconds (10000)\n"
 		"        -A               ignore 1st req for resp time measurements\n"
@@ -50,7 +50,8 @@ static void  hld_usage(char *name, int argc)
 		"URL format:\n"
 		"        (http|https|quic)://<addr>:<port>/<path>\n"
 		"Note: Options marked with an asterisk (*) are positional and MUST be placed\n"
-		"      BEFORE the URLs they are intended to affect.\n",
+		"      BEFORE the URLs they are intended to affect.\n"
+		"Note: When <arg_rate> is set, <arg_thrd> must be lesser or equal to <arg_usr>\n",
 		name);
 	exit(1);
 }
@@ -655,14 +656,10 @@ void haproxy_init_args(int argc, char **argv)
 		goto leave;
 	}
 
-	if (arg_thrd > arg_usr) {
-		ha_alert("Thread count must not exceed connection count\n");
-		goto leave;
-	}
-
 	/* "global" section */
 	hbuf_appendf(&buf, "%.*s", (int)gbuf.data, gbuf.area);
-	hbuf_appendf(&buf, "\tnbthread %d\n", arg_thrd);
+	if (arg_thrd != 0)
+		hbuf_appendf(&buf, "\tnbthread %d\n", arg_thrd);
 	if (arg_mreqs)
 		hbuf_appendf(&buf,
 		             "\ttune.h2.be.max-concurrent-streams %d\n", arg_mreqs);